5.1.11 Server Response to Signals

On Unix, signals can be sent to processes.
mysqld responds to signals sent to it as
follows:

SIGTERM causes the server to shut down.

SIGHUP causes the server to reload the
grant tables and to flush tables, logs, the thread cache, and
the host cache. These actions are like various forms of the
FLUSH statement. The server
also writes a status report to the error log that has this
format: